The new iMac is attractive, but makes compromises in the pursuit of thinness.

Keyboard and mouse

We'll devote a small amount of time to the keyboard, mouse, and trackpad here for the benefit of those of you who have never used an iMac before. For those of you who have, they're pretty much exactly the same as the accessories Apple has been shipping for the last couple of years.

The default accessories are a short Bluetooth keyboard with no number pad and the Magic Mouse, a Bluetooth-enabled mouse with a multitouch-enabled surface that allows for scrolling and a few basic gestures. The keyboard uses the same layout as Apple's laptop's, but the keys have more travel to them. It's overall a bit more pleasant to type on.

Optional accessories include a longer USB version of the same keyboard with a number pad and Apple's Magic Trackpad, which offers all of the multitouch gestures afforded by Apple's laptops in a larger, more desktop-friendly package. Each of these accessories can be swapped for the default ones at no charge when you purchase an iMac from an online or physical Apple Store.

As for which mouse we recommend? It depends on the intended user. As a general rule, more casual users and those coming from Windows PCs will probably prefer the mouse, which (after you enable right-clicking and disable "natural" scrolling) will operate pretty much as a standard two-buttons-and-a-scroll-wheel mouse would. Power users, MacBook owners, and longtime OS X adherents will probably find the trackpad more useful, since it supports OS X's full range of multitouch gestures, and regular use of these gestures is key to getting the most out of the operating system.

Internals and performance

Traditionally, when comparing a computer to its year-and-a-half-old predecessor, you're going to be talking about across-the-board performance increases. In some ways, the 2012 iMac meets those expectations; in others, it is less impressive. We'll start with the good stuff.

First, some elements are similar to last year's model. The 2012 iMac includes dual-band 802.11n with three MIMO antennas, capable of theoretical speeds of up to 450Mbps depending on the capabilities of your router. The 2012 iMac uses a Broadcom Wi-Fi chip rather than the Atheros chip in last year's model, but range and throughput were essentially identical in our testing. Bluetooth 4.0 capabilities are also provided by a Broadcom chip.

That said, you also lose a couple of things. The first is the optical drive, but Apple watchers will have seen that coming from miles away—that battle has already been lost, and the Mac Pro is now the only computer in the lineup with an integrated optical drive. Much more damning is the loss of user-upgradeable RAM. The older aluminum unibody iMacs featured four user-accessible RAM slots in the bottom of the machine—these officially supported 16GB of memory in the 2011 models, but they could be upgraded all the way to 32GB with no ill effects.

The 27-inch model retains its four RAM slots and that (now official) 32GB RAM ceiling; the 21.5-inch model does not. Teardowns have shown the RAM isn't soldered to the logic board as it is in newer MacBook Airs and MacBook Pros, but the two slots can only be accessed by completely taking the machine apart (a time-consuming task that is basically impossible for end users). The 21.5-inch iMac can be upgraded to 16GB of RAM at purchase for $200; 16GB of RAM in two 8GB DIMMs costs about $60 on the open market.

The 8GB of RAM that now comes standard in all iMacs is in less dire need of upgrading than the 4GB of RAM that came standard last year. It's just sad to see that, even in a desktop computer, we're entering an age of hyper-inflated, OEM-defined RAM prices that end users can't choose to fight by purchasing their own upgrades.

CPU

Last year's iMacs saw the adoption of quad-core CPUs across the line and the 2012 iMacs continue that tradition, swapping out the processors using the old Sandy Bridge architecture to the newer Ivy Bridge. These chips have been around for most of this year now and don't really have any surprises left for us. They're a bit quicker than Sandy Bridge CPUs at the same clock speed, and the chips in the new iMacs also get a small clock speed bump relative to last year's Macs—a 2.7GHz Core i5 in our entry-level model, up from a 2.5GHz Core i5 in last year's.

As expected, the Ivy Bridge CPU is a nice bump up over the older model, though if you've got a 2011 iMac, your machine is still plenty fast. Especially if you've got a Core 2 Duo-based iMac from 2009 or earlier, this year's model will give you a big processor speed boost if you upgrade. We've included numbers from the first unibody iMac, which ran a 3.06GHz Core 2 Duo E7600 CPU with 4GB of 1066MHz DDR3, just so you can see what kind of a boost you'd be getting.

GPU

While the CPU numbers are quite nice, the GPU numbers are less exciting, at least for the entry-level model. While the NVIDIA GeForce GT 650M in the high-end 21.5-inch iMac is the same chip as is used in the 15-inch MacBook Pro and Retina MacBook Pro, the GeForce GT 640M in the entry-level model is a fair bit weaker.

The GPU test in Cinebench shows the 640M falling a bit behind the AMD Radeon HD 6750M in last year's entry-level iMac. To further explore the GPU's performance, we installed a 64-bit copy of Windows 8 via Boot Camp and ran our standard suite of 3D and gaming benchmarks.

Name

CPU

Graphics

RAM

Storage

Driver version

2012 iMac

2.7GHz Intel Core-i5 3330S

512MB Nvidia GeForce GT 640M

8GB 1600MHz DDR3

1TB 5400RPM HDD

Nvidia GeForce 305.61, dated 8/6/2012

2011 iMac

2.5GHz Intel Core i5-2400S

512MB ATI Radeon HD 6750M

8GB DDR3

500GB 7200RPM HDD

AMD Catalyst 10.8

The driver we used for testing is the latest beta version available from Nvidia. The version that is installed along with Boot Camp is just a few months older, but it crashed while running one of our games, and the latest stable version of the driver doesn't support the GPU in our iMac. To test, we used the same methodology we applied when we benchmarked Windows 8's performance back in October. Crysis isn't included because it completely refused to run on our system, consistently crashing regardless of what drivers we used.

Running actual games on the GPU paints a more favorable picture—in both Portal 2 and Arkham City, the GeForce GT 640M in the 2012 iMac pulls ahead very slightly and the 3DMark benchmark shows it slightly ahead as well. It does fall behind the 2011 iMac by a significant margin in Minecraft—it's still playable, but you may still run into titles that run better on last year's entry-level iMac than on this one. The higher-end 21.5-inch and 27-inch iMacs all use much more powerful GPUs and should be able to eliminate this ambiguity, but we'll take a closer look when our 27-inch models are in.

Andrew Cunningham / Andrew has a B.A. in Classics from Kenyon College and has over five years of experience in IT. His work has appeared on Charge Shot!!! and AnandTech, and he records a weekly book podcast called Overdue.